Systemic lupus erythematosus Flashcards
What is HLA?
Human Leukocyte Antigen complex
The proteins produced from these genes are present on the surface of almost all cells
On the cell surface, these proteins are bound to protein fragments (peptides) that have been exported from within the cell
MHC class I proteins (HLA-A, HLA-B, HLA-C) display these peptides to the immune system
If the immune system recognizes the peptides as foreign (such as viral or bacterial peptides), it responds by triggering the infected cell to self-destruct
How does damage occur in autoimmune disease?
Circulating autoantibodies will recruit and activate complement, natural killer cells and phagocytes
T lymphocytes are activated, causing direct cell killing and also recruiting other cells
Basically, exaggerated immune response causes bystander damage to self
What classification of hypersensitivity is SLE?
Type 3
Why does glomerulonephritis occur in SLE?
Antibody-antigen complexes are distributed in the walls of small vessels in the glomerulus
This activates complement, and infiltration of neutrophils and macrophages into vessel walls
What is the fundamental immunological abnormality in SLE?
Disturbed B cell regulation
In which patients is SLE most prevalent?
Females
2nd or 3rd decade of life
Asians, Afro-Americans, Afro-Caribbeans and Hispanic Americans
What are anti-nuclear antibodies?
Group of antibodies that bind to nuclear proteins
How effective is screening of anti-nuclear antibodies in diagnosing SLE?
ANA is present in normal, healthy individuals, particularly elderly patients
Titre of 1:160 or greater is significant, but must fit clinical picture to confirm SLE
Which antibody is very specific to SLE?
Anti-dsDNA
What diseases can have a positive ANA result?
SLE Scleroderma Sjogren's syndrome Polymyositis or dermatomyositis Mixed connective tissue disease Autoimmune hepatic disease Malignancy Inflammatory diseases
Which markers in the blood indicate that SLE is active?
High anti-dsDNA titre
Low complement
Why is complement low in active SLE?
Blood tests for complement measure inactive levels
In SLE, the antibody-antigen complexes activate the classical complement pathway, using most of the inactive complement in the inflammatory cascade
What are some of the general systemic symptoms of SLE?
Fever Malaise Poor appetite Weight loss Fatigue
What are some of the musculocutaneous symptoms of SLE?
Photosensitivity Discoid lupus erythematosus Malar rash Mouth ulcers Raynaud's phenomenon Alopecia
What are some of the musculoskeletal features of SLE?
Polyarthritis/polyarthralgia
Rheumatoid arthritis symptoms N.B. no radiological changes
Myopathy - weakness, myalgia & myositis
